Optimal locations and parameters of gastric electrical stimulation in altering ghrelin and oxytocin in the hypothalamus of rats.
Gastric electric stimulation (GES) has been shown to decrease gastric tone and antrum motility, delay gastric empty, suppress appetite and induce weight loss in animal models. Our previous studies have shown that GES activates gastric-distension responsive neurons in several satiety related hypothalamic nuclei; Two hour acute GES at gastric antrum can alter the expression of anorexigenic and orexigenic peptides in the hypothalamus of rats.


OBJECTIVE
To investigate the effects of GES with different stimulation parameters and locations on the neuronal expression of a hunger hormone, ghrelin and a satiety hormone, oxytocin (OT) in the hypothalamus of rats.


METHODS
With immunohistochemical technique, changes in expression of satiety-related peptides-containing (OT- and ghrelin-) neurons with GES in the rodent hypothalamus were assessed. GES was performed for 2h using six different sets of parameters at three different locations.


RESULTS
(1) The number of ghrelin/OT-immunoreactive (IR) neurons was significantly decreased/increased with GES of the standard parameters (pulse trains: train on-time of 2s, off-time of 3s, pulse amplitude of 6 mA, width of 0.3 ms and frequency of 40 Hz) in both the paraventricular nucleus (PVN) and the superoptical nucleus (SON) compared with the control group, but not with GES of reduced pulse amplitudes, frequencies or train-on times. (2) GES with the standard parameters at the antrum resulted in a significant decrease/increase in the expression of ghrelin/OT in the PVN and the SON. However, GES at other locations (middle of lesser curvature or greater curvature) was not effective in altering the expression of ghrelin/OT.


CONCLUSIONS
GES with the standard parameters delivered at the distal antrum increases/decreases oxytocin/ghrelin in the hypothalamus of rats. GES with reduced parameters or delivered at the middle of the stomach is ineffective in altering these peptides.
Zhang
Jing
J
Veterans Research and Education Foundation, VA Medical Center, Oklahoma City, OK, United States.
Liu
Suhuan
S
Tang
Ming
M
Chen
Jiande D Z
JD
D000704:Analysis of Variance; D000818:Animals; D001703:Biophysics; D002452:Cell Count / Q000379:methods; D004525:Efferent Pathways / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods*; D005786:Gene Expression Regulation / Q000502:physiology; D054439:Ghrelin / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism; D010121:Oxytocin / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism*; D011706:Pyloric Antrum / Q000294:innervation*; D051381:Rats; D017208:Rats, Wistar; D013495:Supraoptic Nucleus / Q000166:cytology / Q000378:metabolism*
D054439:Ghrelin; D010121:Oxytocin